1. Field of the Invention
This invention relates to fluid pumps, particularly to high pressure fluid pumps, more particularly to high pressure fluid pumps having relatively high cycle speed.
2. Description of Field of Art
A number of types of pumps have been proposed for use in producing flows of high pressure fluid such as that used in fluid jet cutting nozzles. For use in such applications a pump must produce a fluid pressure of at least 20,000 psi with ability to produce pressures of 60,000 psi or greater for greater efficiency. Additionally, the pump should require minimum maintenance and possess a high degree of freedom mechanical failure. While present applications using fluid cutting jets depend on the unique ability of the cutting jet as compared to conventional cutting methods, it is anticipated that a great many new applications would appear if the cost were low.
The primary apparatus proposed to fit the above parameters is the hydraulically driven plunger pump, which is also called an intensifier. Intensifiers require expensive hydraulic drive systems connecting a source of mechanical power and the pumping apparatus. Intensifiers must also be operated at low speed to enhance component life and are, therefore, not usable for high volume production at low cost. The alternate pressurization and depressurization cycles of the intensifier subject the material of which the intensifior is constructed to alternate compression and expansion. This expansion and compression leads to metal fatigue of the cylinder and similar parts within an unacceptable short period of time if greater speeds are attempted. Similarly, the cycle speed must be kept low to preserve the seals used in the intensifier. The great costs of current intensifiers and, particularly, the hydraulic drive system required has limited the use of cutting tools to applications where pump costs are small factors.
It has been proposed that a small pump operating at engine or motor speed would be capable of producing the same output as a low speed intensifier pump without use of a hydraulic drive system. To date, however, the problems of seal wear and metal fatigue have prevented the successful construction of such a pump, let alone the commercialization of such a pump. Accordingly, there is a need for a high speed, ultra high pressure pump not subject to metal fatigue and seal wear.